C A DH |
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,O, |
! & Q ! !W |
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1 2πT |
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K(0, 0) = 1 ns = 4πnse2 |
= |
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∆2 |
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λ2 |
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n |
m |
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λ2 |
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(ε2 + ∆2)3/2 |
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& QL |
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L |
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L |
n |
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n |
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2 |
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λ2 |
= |
mc |
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$ * |
2 |
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L |
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4πne |
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! * T = 0& |
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H & I ! !W |
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1 |
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Jµ(qω) = − |
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Kµν (qω)Aqν ω |
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& QO |
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4π |
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* ! ( W |
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E = |
− |
∂A |
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Eqω = iωAqω |
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& L |
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∂t |
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! ! # ! W |
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σµν (qω) = − |
1 |
Kµν (qω) |
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σ(qω) = |
1 |
K(qω) |
& L, |
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− |
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4πiω |
4πiω |
* & # *
( q → 0
( !* ! * # ( &
M *) *) #W
σ(ω) = σs(ω) + σexc(ω)
K(0)
σs(ω) = − 4πiω
$ ! #
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σ (ω) = |
− |
1 |
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K(ω) − K(0) |
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4π |
iω |
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exc |
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$ ! # * & ! & LI * ! & QL
W |
nse2 |
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σs(ω) = |
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i |
δ → +0 |
& L |
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, |
m |
ω + iδ |
W |
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nse2 |
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Reσs(ω) = |
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πδ(ω) |
& L |
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m |
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* !* * ! # & &
! &
G ! # !* ! ) σexc(ω) $ !
*
( ! (
& N ! * # & , &
iωm → ω + iδ q → 0& H! !W
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Qαα(ωm, q) = −2 3m2 T |
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n |
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(2π)3 |
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p + 2 |
2 |
× |
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e2 |
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d3p |
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q |
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q |
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q |
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q |
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εn + ωmp + |
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q |
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× G εnp − |
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G |
εn + ωmp + |
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+ F |
εnp − |
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F |
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& LQ |
2 |
2 |
2 |
2 |
') # # %* # *! ! ! ) !* * ξp ≡ ξ(p)
N ! p ≈ pF !
& # ! ! * ! *)
& iωm → ω + iδ ! * !W
Qαα(ωm, q) = −3m2 νF pF2 −∞ dξp |
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εpεp+q |
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{n(εp) − n(εp+q )} × |
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2e2 |
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∞ |
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εpεp+q + ξpξp+q + ∆2 |
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× |
εp − εp+q + ω + iδ + |
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εp − εp+q − ω − iδ + |
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1 |
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1 |
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3m2 |
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F |
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F |
−∞ |
p |
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εpεp+q |
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{ |
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− |
p |
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− |
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p+q } × |
+ |
2e2 |
ν |
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p2 |
∞ dξ |
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εpεp+q − ξpξp+q |
− ∆2 |
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1 |
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n(ε |
) |
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n(ε |
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× εp |
+ εp+q + ω + iδ |
+ εp + εp+q − ω − iδ |
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1 |
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1 |
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& LL |
εp = ) |
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ξp2 + ∆2 |
$ ( ! TK |
& L n(εp) $ %* N ! ( ! !& T → 0 #
# ! # * n(εp) → 0 T → 0 $
TK & ! * q → 0
* # * # % & & %
% * ( ! & 5 ! ! ! * !
* # ! # ! & LI & L &
# # ! δ $ %* *
& L ! ns = n & & ) ( &
} "
" " ( 3 +
2 i8 % = mvi = pi − ec A(ri) 6
= |
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e2 |
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e |
< pi > − |
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J = e < vi >= |
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A(ri) |
(? 7H,+ |
m |
mc |
i |
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i |
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i |
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1 % |
E(rt) = Eeiqr−iωt |
= |
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e2 |
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J(rt) = σ(ω)E(rt) − |
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nA(rt) |
(? 7,*+ |
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mc |
2 E = −1 ∂A(rt)
c ∂t
A = icω E 6 ; (? 7?B+ ns = n ( T = 0+ (? 7,*+
σ(ω) = 0 9 % (? 7HH+
G ( !* # ! ! *
# * ! ! ! @&v&p[w ,O Q & '
*) #! ! & 3 # * ! * !
* ! ) # 1 !2 +J-& #
* ! & & L, & IO ! ! W |
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σ(ω) = lim |
Q(qω) |
, |
Reσ(ω) = |
1 |
ImQ(0ω) |
& O, |
iω |
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q→0 |
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ω |
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! ! !*) # & LL * ω > 0& K ! * ! 1 !2 ! * # p p + q ) 1 ! 2 !
C A DH ,OI
! ( & 5 ! # ( ! ξp ξp+q & LL * # 5 ! ! #W
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Reσ(ω) = ω0 |
−∞ dξp |
−∞ dξpδ(ω − εp − εp ) |
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−εpεp |
− |
= |
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C |
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∞ |
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∞ |
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εpεp |
ξpξp |
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∆2 |
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= |
ω0 |
∆ |
dε ∆ |
dε N (ε)N (ε )δ(ω − ε − ε ) 1 − εε |
& O |
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C |
∞ |
∞ |
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∆2 |
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ξ )
* & L ε # TK *)
&QO & & O C0 *) * ! # * 1 2 ! #) ! # ! ! ∆ → 0 & H & O !
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! #) δ $ %* * !W |
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ε(ω − ε) |
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Reσ(ω) = ω0 θ(ω − 2∆) ∆ |
dεN (ε)N (ω − ε) 1 − |
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= |
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C |
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ω−∆ |
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∆2 |
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ω |
− |
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∆ |
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(ε2 − ∆2)1/2[(ω − ε)2 − ∆2 |
]1/2 |
& OI |
= |
C0 |
θ(ω |
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2∆) |
ω−∆ dε |
ε(ω − ε) |
− ∆2 |
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G ! x ! #) 2ε = ω + x(ω −
2∆) ! !W |
− |
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− |
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−1 |
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[(1 − x2)(1 − α2x2)]1/2 |
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2 ω |
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& OJ |
Reσ(ω) = |
1 |
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C0 |
θ(ω |
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2∆)(ω |
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2∆) |
1 |
dx |
1 − αx2 |
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α = ω−2∆ |
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ω+2∆ & H & OJ ( %* W |
Reσ(ω) = |
C0 |
[(ω + 2∆)E(α) − 4∆K(α)]θ(ω − 2∆) |
& O |
ω |
! # ! ! ∆ = 0 C0
& O ∆ = 0 & '
! ! # ! ! !W
Reσs(ω) |
≡ |
σ1s(ω) |
= |
1 |
[(ω + 2∆)E(α) − 4∆K(α)]θ(ω − 2∆) |
& O |
Reσn(ω) |
σ1n(ω) |
|
ω |
! % !* 3 $ T s&l[EEBr g&v[=?CCD ,O L
( ! ! ! ! * # !
. & &, &
>% 8
( ! + " " 8
A ? )@ "
5L γ = 21τ = ∆ > 8
' ( T ≥ Tc + ! '
/ ($)B,+ "
" " 8
A ? )@ " " !
δ(ω) 3 (? 7H@+ "
" ! ω > 2∆ 8
" % ! 5L T = 0 % %
-0 " ( ' ∆
% % + |
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! |
)* = |
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∞ |
dωReσ(ω) = |
πne2 |
= |
ωp2 |
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(? 7,B+ |
0 |
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2m |
8 |
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. & &, W 6 # # !
! T = 2K h&c[>wC= l&xBD•a[w ,O L &
ω2 = |
4πe2 |
3 / " % |
p |
m |
" A ? )@ " ! 8 |
|
! " " ! |
-" 0 δ 3 ' 1 (? 7H@+ ! "
! ω > 2∆ (? 7,B+ %
"
S # ! ! TK # ! 4 5 ( ! ! * # * #
& % !
! TK & N ( * * ! #
! *
! % * * ! ( & ! # *)
* ! * *
) ! !* ) !* * * ) !* *
*) ! * *) ! * ! &
M # *) * !* )
* ! ! & 8
( ! ! # *
# !* TK ! ! ) # * +-&
, 6 '
G ! ! % ( $ %
! ! & G ( ! ! * ! # % !* ! * ! I&, I&,L I&QJ & K ! * ! ( ! * % * * ! ( $ % ! ! & 5 #
! # ( ! &
6 d = 1 ( T = 0
*) ! !W
Π(kω) = −2i |
2π |
2π G0(εp)G0(ε + ωp + k) |
&, |
|
dp |
dε |
|
! # 2 * & ( # #
ε * !W
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π |
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ω − ξp+k + ξp + iδ(signξp+k − signξp) |
& |
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Π(kω) = |
1 |
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dp |
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n(ξp) − n(ξp+k) |
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2 |
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ξp ≡ ξ(p) = |
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p |
− µ ( ( |
2m |
* N ! & S * & ) W |
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,& ξp > 0, |
ξp+k < 0 |
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& ξp < 0, |
ξp+k > 0 |
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n(ξp) − n(ξp+k ) = 0& 6 * # k > 0& 5 (
*) W
,& −pF − k < p < −pF
& pF − k < p < pF
,OQ
,OL . P - >JK<== = E J<NU0 < J0 0 G/M< K V<1
' ( ! ! ±iδ ! & & G ( !* & ! # W
Π(kω) = −π |
−pF |
−k ω − |
2km2 − pkm − iδ + π |
pF −k ω − 2km2 |
− pkm + iδ = |
1 |
−pF |
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dp |
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1 |
pF |
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dp |
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m ln |
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− |
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− |
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− |
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= |
2 2 |
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kp |
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k |
2 |
kp |
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&I |
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πk |
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k |
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F |
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F |
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k2 |
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kpF |
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ω + iδ |
k2 |
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kpF |
+ ω + iδ |
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m m |
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2m m |
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2m + m + ω − iδ 2m + m − ω − iδ
. ! ! Π(kω) ω = 0 k = 2pF k = 2pF + q & & q = k − 2pF , |q| 2pF & 5 W
Π(k = 2pF + q, ω = 0) = − |
m |
ln |
4pF |
= − |
m |
ln |
4pF |
&J |
πpF |
|q| |
πpF |
|k − 2pF | |
|
N ( * # * * ! ! I&Q
# ! * ! 1 2 ! &
5 # ! * ) ! %
& / ! % *) %* ) 8 & I&,L I&QJ W
|
D−1(kω) = D0−1(ωk) − g2Π(kω) |
& |
k = 2pF # * &J ! !W |
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ω2 − ω22pF |
+ |
mg2 |
ln |
4pF |
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= 0 |
& |
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ω22pF |
πpF |
|k − 2pF | |
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1 − πpF |
ln |k − 2pF | |
&Q |
ω2 = ω22pF |
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mg2 |
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4pF |
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S ) k 2pF
% ! ! ω2 < 0 & M! # %
k 2pF ) ! 1! 2 ! 1 ! !2
. & &, *) * %
!* ! % ! # & S
! * ! ! ! ! ! *
! ! 2π = π & & 4 6
2pF pF
- % ! Reei2pF x cos(2pF x+φ)& ! !
- - * * & ' ! ! ! !
! * ( W ρ(x) = ρ0 + ρ1 cos(2pF x + φ)
1- ns; & ( )
* . & & &
. # ! ! * #
! * T = Tp0 ω2(k = 2pF )
* #& Z # ( ! ! * )
T = 0& . ! ! * & 6 %* 8 %
# ! * 6 W
D−1(kωm) = D0−1(ωmk) − g2Π(ωmk) |
&L |
2 Π(ω, k ≈ 2pF ) ω = 0
% "
. P - >JK<== = E J<NU0 < J0 0 G/M< K V<1
. & &IW R * N ! ( !
! ! & 1G #2 N ! !*) )
( (−pF , pF ) &
D0(kωm) = |
|
ω2 |
, ωm = 2πmT |
|
k |
(iωm)2 − ωk2 |
G W |
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2π G0(εnp)G0(εn − ωm, p − k) |
Π(kωm) = 2T |
n |
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dp |
|
4 * # k 2pF !W
k = 2pF + q, |q| 2pF
G # * *) (%% ) ( ! #
* * N ! # ! # * ! ! #
*) . & &I& 5 ! !W
ξp−k = −ξp + vF q |
|
p +pF |
|
ξp+k = −ξp + vF q |
|
p −pF |
&, |
N ( ) ( !
! ! * 1 2 N ! 1 2 N ! & '
! ! * # k > 0 W
Π(qωm) = T N (EF ) |
n |
−∞ 2πi 2πi iεn |
|
ξp i(εn |
|
ωm) + ξp |
|
vF q = |
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∞ dξp |
|
1 |
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1 |
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− |
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− |
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− |
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signεn |
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θ[εn(εn − ωm)] 2εn |
− |
ωm |
+ ivF q |
&,I |
= −2πT N (EF ) |
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n |
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